The potentially important phyllanthostatin-type antineoplastic glycosides were first discovered by George R. Pettit (Cancer Research Institute, Arizona State University, Tempe, Ariz.) during previous investigations of the Costa Rican tree Phyllanthus acuminatus Vahl (Euphorbiaceae) as reported in J. Org. Chem., 49, 4258 (1984). Presently, the orthoacid equilibrium product phyllanthostatin 1 phyllanthoside [see: J. Org. Chem.. 50, 5060 (1985)] is undergoing preclinical development by the U.S. National Cancer Institute and total synthesis of phyllanthoside and the aglycone phyllanthocin have been completed. Because of the easily promoted orthoacid rearrangement uncovered during structural elucidation of the phyllanthostatins, it became necessary to reevaluate their abundance, and possibly detect new members of the series, in relatively fresh P. acuminatus roots using the high performance liquid chromatographic analyses photodiode array detector reported in Chromatographia, 15, 419(1982) and J. Chromatogr., 283, 137(1984) at an early stage of separation.
During this ongoing research, a previously unknown lignan glycoside was discovered which is herein denominated "phyllanthostatin A" and which, was found to inhibit growth of the PS leukemia cells in vitro at a concentration of ED.sub.50 =4 .mu.g/ml.